1. Field of the Invention
The present invention relates to scaling a design of an integrated circuit. More specifically, the present invention relates to accurately replicating the design of integrated circuit modules.
2. Description of the Related Art
A microprocessor is a central processing unit of a computer or other device using thousands (or millions) of gates, flip-flops and memory cells. Memory cells are modified versions of basic logic (and, or, xor) gates. Gates are combinations of high-speed electronic switches.
Digital circuits, no matter how complex, are composed of a small group of identical building blocks. These blocks are either basic gates or special circuits such as Schmitt triggers, special memory cells and other structures for which gates are less suitable. But the majority of digital circuits are composed of gates or combinations of gates. A flip-flop, for example, can be considered as a function block, but it is composed of interconnected gates.
Boolean algebra provides information otherwise found in a truth table as equations. Boolean algebra is used to determine alternate logic structures that will perform a desired function. Gates are the electronic equivalent of simple conventional switches connected in series or parallel. Various systems combine groups of these series and parallel switches. A logic diagram shows how logic gates are interconnected. A system can be designed to accomplish a specific function using logic diagrams, truth tables and Boolean algebra. Boolean algebra provides the means to ensure that any given logical requirement is satisfied using a minimum number of gates.
It is known to use commercially available software to model certain features of processor design in software. For example, Table 1 represents the design of a circuit having seven gates in a common language, Verilog, available from Cadence, Inc. in San Jose, Calif.
It is known that software tools can be used to model the design of many integrated circuits. For example, Verilog is a hardware description language (HDL) which can be used to describe digital systems at various levels of abstraction. Verilog is the most predominantly used HDL in the United States. Verilog was originally designed by Gateway Design Automation in approximately 1985. Verilog was made available to the public in 1990 and has been adopted as a standard by the Institute of Electrical and Electronic Engineers (IEEE).
Electronic design automation (EDA) tools were originally designed to simulate logic. As electronic design tools became more popular, vendors began to provide enhanced functions. EDA tools are now used to drive synthesis, timing, simulation, test and other tools. Software tools used to test integrated circuit chips are logic simulator, fault simulator and automatic test pattern generator (ATPG). Other vendors of software tools are: Mentor Graphics (www.Mentor.com), Wilsonville, Oreg.; Snyopsys (www.Synopsys.com), Moutain View, Calif.; and Snytest Technologies, Inc. (www.Snytest.com), Sunnyvale, Calif. These corporations are listed as examples only, other manufactures use proprietary tools for the same purpose.
Due to the logical functions performed by many integrated circuits, the design of these circuits can be replicated to produce circuit designs with more gates. What is needed is a method of modeling which will accurately generate a large design by replicating an existing design while preserving the logic and fault behavior. Accurately replicating a design allows a integrated circuit design to be generated in less time and with less errors.
The present invention teaches a method for designing an integrated circuit. The design of the integrated circuit is replicated a number of times. The number of times must be odd. The input signals to the original module are also replicated. The replicated modules are configured to respectively receive the replicated input signals. A number of exclusive or gates is provided. The exclusive or gates receive the output signals from the replicated modules. The output signals from the replicated modules are compared to the output signals from the original module. The method is applicable to a bi-directional integrated circuit.
Embodiments include the software to replicate the design. Another embodiment includes a computer system for replicating the design. Also, integrated circuits designed by the method described are included within the scope of the disclosure. Another embodiment includes designs produced by the method.
The foregoing is a summary and this contains, by necessity, simplifications, generalizations and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting.